Auger-bit.



. CALDWELL.

, AUGER BIT. APPLICATION FILED JUNE 24, 1908.

Patented July 4, 1911.

COLUMPIA'PLANDGRAPH C0., WASHINGTON. D. C.

pin s JOHN WILLIAM r arr CALDWELL, OF TORONTO, ONTARIO, CANADA.

AUGER-BIT.

Application filed June 24, 1908. Serial No. 440,177.

To all whom it may concern:

Be it known that 1, J OHN WILLIAM CALD- WELL, a subject of the King ofGreat Britain, of the city of Toronto, in the county of York, in theProvince of Ontario, in the Dominion of Canada, have invented certainnew and useful Improvements in Auger- Bits, of which the following is aspecification.

The invention relates to improvements in auger bits as described in thefollowing specification and illustrated in the accompanying drawingsthat form part of the same.

The invention consists essentially in the novel formation of the bit,whereby the spiral channels form free passages for the chips, saidchannels in cross section presenting a flat surface of greater widththan the chi The objects of the invention are to obviate thedifficulties experienced by the choking of bits, to devise a' bit whichmay be sharpened to the extent of the length of the spiral, to insurethe proper feeding of the bit, and generally to facilitate the boring ofholes in wood or like material.

In the drawing Figure 1 is a perspective view of one form of my bitbroken intermediate of its length and showing the formation andarrangement of the side flanges, and also showing a chip resting in thechannel formed in the spiral portion. Fig. 2 is a perspective View ofthe bit shown in Fig. 1 turned slightly from the posit-ion shown in Fig.l and showing the cutting edges and lead screw. Fig. 3 is a crosssection through the bit shown in Figs. 1 and 2. Fig. 1 is a perspectiveView of a slightly modified form of my bit. Fig. 5 is a cross sectionthrough the bit shown in Fig. 4:.

Like numerals of reference indicate corresponding parts in each figure.

Referring to the 8 are the side cutters extending downwardly from thecutters 7 and formed by the side flanges 4 and 5 having the lower andfront edges rounded and sharpened to cut into the wood.

9 is the lead screw centrally arranged and extending downwardly from thespiral l and having a core 10 tapering to a point.

11 are the spiral flanges of the lead screw extending outwardly from thecore 10 and formed with their under surfaces beveled upwardly andinwardly and presenting downwardly extending cutting edges andterminating in a pair of downwardly sloping chisel points 12 extendingbeyond the point of the cone-shaped core 10.

The flanges or threads of the lead screw are formed with the same angleof incline as the spiral 1. The incline of both lead screw and bit maybe varied in various bits to suit the kind of wood in which they are tobe used, that is to say, bits to be used in soft wood may be fed quickerthan if used in hardwood, and a steeper inclined lead screw consequentlyused in the soft wood, or on small sizes of bits or augers.

On inserting the bit into a piece of wood, the cutting points 12 at theend of the flanges ll-cut into the wood and as the bit is turned, theupper sloping side of the flanges 11 draw the bit downwardly forcing thecutters 8 into the wood. As the bit is drawn into the wood by the leadscrew, the cutters 7 are brought into contact with the upper surface andcut away the chip. The width of the chip cut is of course only half thediameter of the bit, and as the flatsurface of the spiral 1 is ofgreater width than half the diameter, the chip will follow the spiralquite freely and not bind between the wall of the hole and the center ofthe bit, nor between the succeeding spirals, or flanges of the bit.

In Fig. 1, 1 have shown a chip resting in the spiral channel showingthat there is considerable clearance between the outer edge of the chipand the outer side of the bit. This formation of the spiral allows thedrawings 1 15 the spiral of the bit formed in cross section of the body2 forming a web with parallel straight faces 3 and connecting thelaterally extending flanges 4: and 5 at the side extremities, saidflanges projecting from opposite faces of the chips to foll0w the spiralStraight from the body respectively and stiffening the same, cuttingedge wlthout be1ng impeded in any said web and flanges forming a pair ofspiral manner and through the pecullar formation of the lead screw thebit is drawn into the wood and does not require any end pressure.

In the form shown in Figs. 4 and 5 the side flanges 13 and 14 extendfrom each side of the body 2, so that there is a flanged channels 6 ofgreater width than half the diameter of the bit and extending throughoutthe length of said spiral. 7 are the cutting edges formed at the lowerend of said spiral 1.

edge at each side of the upper surface. The object of this arrangementis to provide a double side cutter, that is to say, the side cuttingedge 15 extends above and below the horizontally sharpened edge 16 ofthe web portion.

Either form of the bit may be sharpened from time to time as desired byfilling the under beveled surface of the spiral l and sharpening theterminal edge of the side flanges. In the sharpening operation thecentral portion of the web is not cut away, but forms a continuation ofthe flanges 11 and as the said flanges are arranged at the same inclineas the spiral 1 they will continue to follow the central core as long asthe bit is sharpened. It will thus be seen that the bit may be sharpeneduntil the spiral is worn short and the cutting edges will always remainin the same relative position and will also always allow sufficientclearance for the chip both close to the cutters and farther up thespiral;

It will be seen from this description that a bit formed as described hasmany advantages, as no bits at present known, as far as am aware, havesuflicient space between the center portion and the outer side to allowthe chip to pass from the cutter without crowding between the center andthe side of the nole, in other words, the space is usually less thanhalf the diameter of the bit, and as the clip cut is half the diameterof the hole, choking and waste of energy must occur. Further the formsof bits at present known can only be sharpened a few times until thecutters are worn away, when the bit has to be discarded, whereas in thepresent invention the bit is so formed that it may be sharpened untilthe whole bit is used up.

, in the Dominion The form of bit as herein described is equallyadaptable for use in gimlets and small and large bits for variousclasses of work.

WV hat I claim as my invention is 1. An auger bit, comprising, a spiralbody portion having a cross sectional shape showing parallel straightfaces, said straight faces presenting channels of greater width thanhalf the diameter of the bit.

2. An. auger bit, comprising, a spiralbody portion having a crosssectional shape showing parallel straight faces, said straight facespresenting channels of greater width than half the diameter of the bit,said body portion terminating in cutting edges to each side of thecentral lead screw and having flanges forming side cutters at the bottomend.

3. An auger bit, comprising, a spiral body portion having a crosssectional shape showing parallel straight faces, said straight facespresenting channels of greater width than half the diameter of the bit,said body portion terminating in cutting edges to each side of thecentral lead screw and having flanges forming side cutters at the bottomend, said side flanges in cross section appearing as extending laterallyfrom said parallel straightfaces at each end and forming guidingshoulders for the chips in their travel along said channels.

Signed at the city of Toronto in the county of York in the Province ofOntario, of Canada this 16th day of June 1908.

JOHN WILLIAM CALDWELL.

WVitnesses H. DENNIsoN, WM. C. Mum.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

